The previously common wet separators, which were used for the separation of overspray in coating installations, in particular in car body paint shops, are increasingly being replaced, for known reasons that will not be repeated in greater detail here, by electrostatic separator devices such as are described in DE 10 2008 046 414 A1 or also DE 10 2010 007 479 B3, for example. Separator devices of this kind comprise a plurality of separator units, the main component of which in each case is at least one panel-shaped separator electrode. These separator electrodes are arranged at intervals from one another in the separator device, substantially parallel to one another. Located respectively between adjacent separator electrodes is a high-voltage electrode. The application of a high voltage to the high-voltage electrode causes an electrical field to be created between this and the separator electrodes. If cabin air charged with overspray is routed between the separator electrodes, the overspray particles are initially ionised and then guided by the electrical field onto the separator surfaces of the separator electrodes, where they precipitate.
The problem arises here of how the precipitate consisting of overspray is removed to keep the separator surfaces permanently free. Various mechanical systems were used previously for this purpose, which will not be considered in greater detail here. An especially reliable method of removing the overspray precipitate from the separator electrodes consists in permitting a separator liquid to flow in a closed film over the separator surfaces. The overspray particles are taken up in the separator liquid and flow with the separator liquid into a collection vessel, for example. In favourable cases, the overspray can be recovered from the separator liquid collected.
To achieve the desired effect, it is important that the separator liquid flows uniformly and completely over the separator surfaces, so that no areas of the separator surface thus remain free of separator liquid. To do this, an overflow channel is used in DE 10 2008 046 414 A1, already mentioned above, which describes a separator unit of the type stated at the beginning. The overflow channel extends at a height lying above the upper edge of the separator electrode, and is supplied in a suitable manner with a separator liquid. This separator liquid is removed from the channel and then routed to the separator surfaces of the separator electrode in a suitable manner.
DE 10 2008 046 414 A1 describes substantially two possibilities for how the removal of the separator liquid can take place from the channel: firstly the channel is operated as an overflow channel, in which the channel simply overflows its upper edges with an adequate feed of separator liquid. As the second possibility, rolls are described that are arranged with their longitudinal axes in parallel in such a way that they are partially immersed in the separator liquid located in the overflow channel. Upon their rotation, they scoop and carry separator liquid, which is removed from them again at another point by doctor-blade-like devices and is then fed to the separator surfaces of the separator electrodes.
“Active” removal of the separator liquid is basically preferable to “passive” removal due to pure overflow. However, the rotating rolls mentioned above have the disadvantage that their scooping ability, thus the ability to remove separator liquid from the channel upon their rotation, is dependent on material properties of the separator liquid, in particular on its viscosity.